Evaluations on Coastal Topographical Changes at Hualien Coast, Taiwan

Tai-Wen Hsu, Shan-Hwei Ou, Shiaw-Yih Tzang

Abstract


Coastal topographical changes at Hualien Coast, downdrift of Port of Hualien, Taiwan, after the construction of an extended breakwater are closely evaluated based on the results from continuous field survey data, a statistical 2-D empirical eigenfunction model, and a numerical hydrodynamic model for nearshore current fields. Firstly, the analysis from field survey data verifies the significant impacts on shoreline changes due to the installation of an extended breakwater. The 2-D empirical eigenfunction model is then applied to forecast beach profile changes at the coastal areas assuming no breakwater installation. Comparisons with surveyed beach profiles successfully illustrate that the breakwater installation is responsible for giving rise to accreting northern beaches while eroding southern beaches. The numerical result further points out that the extended breakwater induces an extra clockwise circulation cell in harbor's lee marine area and it transports sediment towards the harbor in shallower water. Altogether, clear identifications on the effects of the breakwater installation suggest that detailed and reliable evaluations on the coastal topographical changes can be achieved through adoption of the present schemes.


Keywords


Coastal topographical changes; empirical eigenfunction model; wave-induced nearshore circulation; beach erosion

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